Module:Protect
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 | This module is rated as alpha. It is ready for third-party input, and may be used on a few pages to see if problems arise, but should be watched. Suggestions for new features or changes in their input and output mechanisms are welcome. |
 | This Lua module is used in system messages, and on approximately 218,000 pages. Changes to it can cause immediate changes to the Wikipedia user interface. To avoid major disruption and server load, any changes should be tested in the module's /sandbox or /testcases subpages, or in your own module sandbox. The tested changes can be added to this page in a single edit. Please discuss changes on the talk page before implementing them. |
This metamodule simplifies error handling in other modules. It transforms a function, which may throw an error, into a function, which returns a specified error message in that case.
Usage
local protect = require('Module:Protect')
local protectedFunc = protect(func, errFormat, options)
Arguments
func- Function to be transformed.
errFormat(default:'Error: %s')- Custom error message.
- Use
'%s'to include the message from a caught error.
options– optional table with the following fields:raw(default: false)- If true, then
errFormatwill be used as is, otherwise it will be wrapped inside a tag<strong class="error">.
- If true, then
removeLocation(default: true)- If true, removes location information from caught error messages.
Return value
The resulting protectedFunc is a function, which calls the original function func, passing all arguments to it, and returns all its return values. If func throws an error, the specified error message is returned instead.
Example
local protect = require('Module:Protect')
local p = {}
function p.main(frame)
if not frame.args[1] then
error('missing argument')
end
return frame.args[1]
end
p.main = protect(p.main)
return p
Invoking the main function without arguments will output: Error: missing argument
This module (and the documentation) are based (partially) on Module:Protect from the free encyclopedia wikipedia and is licensed under GNU license for free documentation and the Creative Commons Attribution/Share Alike. On wikipedia there is a List of authors accessible. More about importing from wikipedia on page Imedwiki:Importing from wikipedia.
local function processResult(options, success, ...)
if not success then
local message = tostring(... or '(no message)')
if options.removeLocation then
message = string.gsub(message, '^Module:[^:]+:%d+: ', '', 1)
end
return string.format(options.errFormat, message)
end
return ...
end
local function protect(func, errFormat, options)
if type(errFormat) == 'table' then
options = options or errFormat
errFormat = nil
end
options = mw.clone(options) or {}
options.errFormat = errFormat or options.errFormat or 'Error: %s'
if not options.raw then
options.errFormat = '<strong class="error">' .. options.errFormat .. '</strong>'
end
options.removeLocation = options.removeLocation == nil or options.removeLocation
return function (...)
return processResult(options, pcall(func, ...))
end
end
return protect